Auto-aligning ablating device and method of use

ABSTRACT

An ablation device and methods for use thereof including a support structure adapted to support an ablation structure within an alimentary tract of a patient are provided. The support structure includes a longitudinal support with a longitudinal axis and a rotational support. The rotational support is adapted to permit at least part of the ablation structure to rotate with respect to the longitudinal support&#39;s longitudinal axis.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a divisional of U.S. patent application Ser.No. 11/275,244, filed Dec. 20, 2005, which is a continuation-in-part ofcommonly assigned, co-pending U.S. patent application Ser. No.11/286,257, filed Nov. 23, 2005 and U.S. patent application Ser. No.11/286,444, filed Nov. 23, 2005, the full disclosure of which are fullyincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to medical devices and methods of use thereof, forablating tissue in an alimentary tract.

BACKGROUND OF THE INVENTION

The primary function of the human esophagus is the transport of solidand liquid nourishment from the mouth to the stomach. The esophagus hasinherent coordinated contractile capabilities, providing peristalsis ofmaterial in an antegrade direction (towards the stomach). Further, theesophagus secretes a neutral pH mucous to lubricate the passage of food,as well as to protect its lining from acid induced injury. The stomachcontains a mixture of food and liquid from oral intake, acid and enzymesfrom the stomach lining, and bile and enzymes from the liver andpancreas. The lower esophageal sphincter and diaphragmatic muscles actas a valve at the junction of esophagus and stomach, preventing refluxof stomach contents into the esophagus. This lower esophageal sphincternormally remains closed until parasympathetic activation or approach ofa food bolus causes its relaxation, allowing food to pass into thestomach from the esophagus. Distention of the stomach, particularly thecardiac portion of the stomach, causes an abrupt relaxation of the loweresophageal sphincter resulting in a venting event (belch). Certainfoods, medication, and beverages containing caffeine or theophylline(xanthines) may predispose the lower esophageal sphincter toinappropriate relaxations, and subsequent reflux. Anatomical effectsrelated to aging or hiatal hernia may also predispose a patient toreflux.

Patients having abnormal function of the lower esophageal sphincter maypresent with symptoms of dysphagia (difficulty in swallowing), heartburndue to reflux, chest pain, and other related symptoms. A common sign ofchronic gastroesophageal reflux is erosive esophagitis. When chronicallyexposed to injurious stomach contents, the esophageal lining maybreakdown leading to inflammation, erosion or ulceration. Chronic GERDand the resultant erosive esophagitis can lead to a pre-cancerouscondition, known as Barrett's esophagus or intestinal metaplasia, whichis injury-related genetic change in the epithelial cells.

As described for example in copending, commonly owned U.S. applicationSer. No. 10/754,445, filed Jan. 9, 2004, a treatment catheter having anexpandable electrode support can be used for treating a circumferentialregion of the esophagus in order to ablate an abnormal mucosal layer ofthe esophagus using radiofrequency (RF) energy. When successful, thetreatment results in regeneration of a normal mucosal layersubstantially free from metaplastic and other damaged epithelial cellscharacteristic of Barrett's esophagus.

In some instances, however, such radiofrequency ablation treatment maynot be entirely successful and one or more regions of abnormal mucosamay remain. These focal areas may be approached with a device designedwith a surface area more suited to ablating focal areas of mucosaldisease. Further, some patients with Barrett's esophagus may present atbaseline with very limited disease, either non-circumferential or veryshort segments that also would be better suited for focal ablationrather than circumferential ablation.

SUMMARY OF THE INVENTION

In general, in one aspect, the invention features an ablation device andmethods of use thereof, including an ablation structure and a supportstructure adapted to support the ablation structure within an alimentarytract of a patient. The ablation device support structure includes, inone implementation, a longitudinal support with a longitudinal axis anda rotational support. The rotational support is adapted to permit atleast a part of the ablation structure to move with respect to thelongitudinal support's longitudinal axis.

Implementations of the invention can include one or more of thefollowing features. The rotational support can be adapted to rotate withat least one degree of freedom. In an alternative implementation, therotational support can be adapted to rotate with at least two degrees offreedom. In a further implementation, the rotational support can beadapted to rotate with at least three degrees of freedom.

The rotational support can include a stop member adapted to limit arange of rotational motion. The rotational support can include amovement resistor. In one implementation, the movement resistor includesa spring. In another implementation, the rotational support includes alock adapted to prevent rotational movement of the ablation structure.

In one implementation the ablation device includes an actuator mechanismadapted to prevent rotational movement of the ablation structure.

The support structure can include an endoscope. Alternatively, thesupport structure includes a catheter.

The ablation structure can include at least one electrode. In oneimplementation, a plurality of ablation structures are supported by thesupport structure. In another implementation the ablation structure iscapable of cryogenic tissue ablation.

In general, in another aspect, the invention features a method ofablating tissue in an alimentary tract including the steps of advancingan ablation structure into the alimentary tract; supporting the ablationstructure with a support structure within the alimentary tract; rotatingat least part of the ablation structure away from the support structureand toward a tissue surface; and activating the ablation structure toablate the tissue surface.

Implementations of the invention can include a method of ablating tissuewherein the rotating step includes applying a force between the ablationstructure and the tissue surface. In another implementation, theadvancing an ablation structure step includes advancing a plurality ofablation structures, and the rotating step includes rotating at leastpart of one or more of the plurality of ablation structures by applyinga force between one or more of the plurality of ablation structures andthe tissue surface.

The rotating step can include rotating at least part of the ablationstructure about at least one rotation axis. In one implementation, therotating step includes rotating at least part of the ablation structureabout at least two rotation axes. In a further implementation, therotating step includes rotating at least part of the ablation structureabout at least three rotation axes.

In one implementation, the method of ablating tissue further includeslimiting a rotation range of the ablation structure. In anotherimplementation the method further includes resisting rotation of theablation structure while rotating the ablation structure. In anadditional implementation, the method further includes locking theablation structure to prevent rotation of the ablation structure.

The step of advancing the ablation structure can include advancing anendoscope into the alimentary tract. In one implementation thesupporting step includes supporting the ablation structure with theendoscope.

In one implementation the ablation structure includes at least oneelectrode, and the activating step includes supplying electrical energyto the electrode. In another implementation, the ablation structure iscapable of cryogenic ablation, and the activating step includessupplying a super-cooled fluid to the ablation structure.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe appended claims. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a view of the ablation device of the invention includingcoordinate axes illustrating freedom of movement.

FIG. 2A is a cross-section view of a structural support including arotational support and coordinate axes illustrating freedom of movement.

FIG. 2B is a cross-section view of a structural support including analternative rotational support and coordinate axes illustrating freedomof movement.

FIG. 2C is a view of an alternative rotational support including analternative rotational support and coordinate axes illustrating freedomof movement.

FIG. 2D is a view of an alternative structural support including analternative rotational support.

FIG. 2E is a view of an alternative structural support including analternative rotational support and coordinate axes illustrating freedomof movement.

FIG. 3A is a view of the ablation device of the invention.

FIG. 3B is a view of an alternative rotational support.

FIG. 3C is a view of another alternative rotational support.

FIG. 4A is a view of the ablation device of the invention combined withan endoscope in the context of an alimentary tract.

FIG. 4B is a view of the ablation device of the invention including alip feature and an electrode trace combined with an endoscope.

FIG. 4C is a view of the ablation device of the invention including alip feature, ports and lines combined with an endoscope.

FIG. 5 is a view of the ablation device of the invention including astructural support with two rotational supports, two longitudinalsupports, and tow ablation structures combined with an endoscope.

FIG. 6 is a view of the ablation device of the invention including amovement resistor.

FIGS. 7A-B are views of the ablation device of the invention includingan alternative movement resistor.

FIGS. 8A-B are views of the ablation device of the invention includingalternative movement resistors.

FIGS. 9A-B are views of the ablation device of the invention includingalternative movement resistors.

FIG. 10 is a view of the ablation device of the invention includingalternative movement resistor.

FIGS. 11A-C are views of the ablation device of the invention includingalternative movement resistors.

FIG. 12 is a view of the ablation device of the invention including anactuator mechanism.

FIG. 13 is a view of the ablation device of the invention connected toan endoscope.

FIGS. 14A-B are views of an alternative embodiment of the ablationdevice.

FIG. 14C is an end view of the ablation device shown in FIGS. 14A-B.

DETAILED DESCRIPTION OF THE INVENTION

Apparatus and methods for ablating tissue within an alimentary tract ofa patient or subject, using an ablation device including a supportstructure adapted to support an ablation structure within the alimentarytract are provided. The support structure of the ablation deviceincludes a longitudinal support having a longitudinal axis and arotational support. The rotational support is adapted to permit at leasta part of the ablation structure to rotate with respect to thelongitudinal support's longitudinal axis. In accordance with the presentinvention, the ablation device is advanced into the alimentary tract.Optionally, the ablation device can be supported at the distal end of anendoscope. The ablation structure is rotationally deflectable toward atissue surface and the ablation structure is activatable to ablate thetissue surface. Within the alimentary tract, variously sized tissuesurface sites, can be selectively ablated using the apparatus andmethods described herein.

For the purposes of this disclosure, any components made up of mucousmembrane and muscle extending between the mouth and the anus;functioning in digestion and elimination are contemplated as part of thealimentary tract. Such components include but are not limited to theesophagus, stomach, small intestine, appendix, large intestine, colon,rectum and anal canal.

As shown in FIG. 1, in general, the ablation device 100 of the inventionincludes a support structure 111 capable of supporting an ablationstructure 130. The rotational support 116 includes a longitudinalsupport 114 that has a longitudinal axis and supports the ablationstructure 130. The rotational support 116 is adapted to permit rotationof at least a part the longitudinal support 114 in relation to itslongitudinal axis to permit at least a part of the ablation structure130 to rotate. The longitudinal support 114 rotation as permitted by therotational support includes but is not limited to, for example,rotating, pivoting, turning or spinning. It is envisioned that thelongitudinal support 114 can be rotated away from, toward or along thesupport 114 longitudinal axis.

As further shown in FIG. 1 by a representation of the longitudinalstructure 114 x, y and z coordinate axes, the rotational support 116 canpermit the longitudinal structure 114 to move in several possibledegrees of freedom. Although only a single arrowhead showing possiblerotation about each axis is shown in FIG. 1 and subsequent figures, itis intended that bi-directional rotation about a given axis isrepresented.

As shown in FIGS. 1 and 2A, the rotational support 116 can beconstructed and arranged such that the longitudinal structure 114 isfree to rotate with three degrees of freedom. The three degrees offreedom are indicated on the three axes, x, y, and z. In these andsubsequent figures, a “yes”-labeled axis indicates bi-directionalfreedom of movement about the axis, whereas a “no”-labeled axisindicates no freedom of movement about the axis. It is envisioned thatthe rotational support can be adapted to rotate with at least one degreeof freedom, with at least two degrees of freedom, or at least threedegrees of freedom. It is further envisioned that the ablation devicecould be constructed and arranged to provide linear movement or afloating movement of the longitudinal structure along the x, y or zplane (not shown). For example, a sponge or compliant longitudinalsupport would allow for linear compression in the y direction (notshown).

As shown in FIGS. 2B-E, the rotational support 116 can be constructedand arranged such that the longitudinal structure 114 is free to rotatewith two degrees of freedom. In the embodiments of FIGS. 2B and 2D, thelongitudinal support is free to rotate about the x and y axes but notthe z axis (see coordinate axes illustration in FIG. 2B and x and y axesindicated in FIG. 2D). In the embodiments shown in FIGS. 2C and 2E, thelongitudinal support is free to rotate about the x and z axes but notthe y axis.

As shown in FIG. 5, the structural support 111 can include a singlerotational support 116 coupled with two longitudinal supports 114, eachsupporting an ablation structure 130. The longitudinal support 114 andbase 112 can be made of compliant materials including but not limited tosilicones or urethanes. It is envisioned that the ablation device 100can alternatively include two or more longitudinal supports 114 coupledwith one or more rotational supports 114.

The rotational support can further include a base 112 portion as shownin FIGS. 1, 2A, 2B, 2D, 2E, 3A-C, 4A-B, 5, 6, 7A-B, 8A-B, 9A-B, 10,11A-C, 12 and 14A-C. As discussed in detail below, in general, the base112 is constructed and arranged to provide a means of attaching orconnecting the ablation device 100 to an elongate member including butnot limited to, for example, an endoscope or catheter.

A portion of the rotational support 116 can be constructed and arrangedto include any of a number of shapes and structures for connecting therotational support 116 to the longitudinal support 114 and providingrotational movement to the longitudinal support 114. Possible shapesinclude but are not limited to, for example, a rounded shape, a sphere,a constant diameter cylindrical shape, a variable diameter cylindricalshape and an oblong sphere shape. Possible structures include but arenot limited to, for example, one or more hinge, spring, universal-joint,ball joint or pin joint.

As shown in FIGS. 1, 2A, 4B and 5, in one embodiment the rotationalstructure 116 can include a ball-shaped portion that can be set into arecess or receiver such as, for example, a socket in the longitudinalsupport 114. In another embodiment, as shown in FIG. 2B, the rotationalstructure 116 can include a ball-shaped portion having a projection 117feature. In this embodiment the projection 117 engages a slot 115feature of the longitudinal support 114 thereby permitting rotation ofthe longitudinal support 114 in two axes, the x and y axes, but not inthe z axis. Engagement of the projection 117 with the slot 115 of thelongitudinal support prohibits rotation of the longitudinal support 114about the z axis.

In another embodiment, as shown in FIG. 2C, the rotational support 116can include an elongate sphere or football-shaped portion. As indicatedin the coordinate axes illustration, the embodiment depicted in FIG. 2Cis constructed and arranged to permit rotation of the longitudinalsupport 114 (not shown) in relation to two axes. As shown, rotation ofthe longitudinal support 114 (not shown) can occur in the x and z axesbut not in the y axis.

As shown in FIG. 2D, in yet another embodiment the support structure 111can include a universal joint having a pin 119 and a rotational support116. As indicated, this embodiment permits rotation of the longitudinalsupport 114 (not shown) in the x and y axes. It is envisioned that twoor more universal joints could be included in the support structure 111.As shown in FIG. 2E, in a further embodiment the rotational structure116 can includes a spring. As indicated in the coordinate axesillustration, this embodiment permits rotation of the longitudinalsupport 114 in the x and z axes but not in the y axis.

As shown in FIGS. 3A-C and 14A-C, in other embodiments the supportstructure 116 can include a structure comprising a pin 119. It isenvisioned that the pin 119 can pass through a portion of thelongitudinal support 114, the rotational support 116, and in some casesthe base 112 (or connecting element 120 of the base 112) of the supportstructure 111, thereby connecting the longitudinal support 114 and therotational support 116. Rotation about the pin 119 by the longitudinalsupport 114 provides rotation of at least a part the longitudinalsupport 114 in relation to its longitudinal axis. It is envisioned thatone or more universal joints can be used in conjunction with one or morepins 119 to provide rotational movement to the longitudinal support (notshown).

As shown in FIGS. 14A-B, where the support structure 116 comprises a pin119, rotation of the longitudinal support 114 about the pin 119 caninclude a range of movement of the longitudinal support 114 from aneutral position (see FIG. 14A) to a tilted or angled position (see FIG.14B). Both the neutral and angled positioning can be useful fortreatment of a tissue surface. The neutral position, which includes alow profile, is particularly useful for introduction and/or removal ofthe ablation device 100 from a treatment site.

As shown in FIG. 3B, in another embodiment the rotational support 116 inaddition to including a pin 119 includes a spring 124 (e.g., a torsionspring) coupled to the pin 119. As shown in FIG. 3C, in yet anotherembodiment the rotational support 116 in addition to including a pin 119includes a movement resistor 123 coupled to the pin 119. In thisembodiment, the movement resistor 123 can be made up of any of a numberof resistive or compliant substances or structures capable of returningthe pin to a desired position after a period of pin 119 deflection orrotation. Suitable structures include but are not limited to sleeves orbushings, for example a silicone sleeve or bushing. Suitable materialsfor encasing or bonding a pin include but are not limited to silicone,urethane or other polymers. Other suitable materials and structures arewell known to those of skill in the art.

It is envisioned that the structural support can include combinations ofany of the rotational support 116 features described herein.

The base of the rotational support can be constructed and arranged inany of a number of ways to support the ablation device. In someembodiments, the base is constructed and arranged to connect thestructural support of the ablation device to another device such as aconventional endoscope. For example, the base can be constructed andarranged to attach the ablation device to an outside surface of anendoscope. Alternatively, the base can be constructed and arranged toattach the ablation device to an inside surface, an outside or insidefeature of an endoscope, or any combinations of the above. In someembodiments, as shown in FIGS. 1, 3B-C, 4A-B, 6, 7A-B, 8A-B, 9A-B, 10,11A-B, and 12, the base 112 is constructed and arranged as a sheath. Ina particular embodiment, the base 112 includes an elastomeric sheath. Inother embodiments, as shown in FIGS. 3A and 14A-C, the base 112 includesa connecting element 120 and a band or strap 126. In one embodiment thestrap 126 is an elastomeric strap. The connecting element 120 canprovide an attachment point between the base 112 and the longitudinalsupport 114. The strap 126 can be attached to the connecting element 120and function, for example, as a way of attaching an endoscope. Theconnecting element 120 and the strap 126 can be made up of the same ordifferent materials if desired. As shown in FIGS. 14A-C, the connectingelement 120 can include a tapered or sloped portion that angles up tothe longitudinal support 114. As illustrated, in one embodiment thetapered portion of the connecting element 120 is positioned opposite topin 119 on the connecting element 120 of the base 112. The taperedportion of the connecting element 120 can function to enable easyremoval of the ablation device 100.

As shown in FIGS. 4B-C, in one embodiment rotational support base 112includes a stop or lip 113 feature. The lip 113 can be constructed andarranged to function as a stop designed to aid in positioning theablation device 100 in relation to an accessory device such as anendoscope 127 as shown. In the example shown in FIGS. 4B-C, positioningthe endoscope 127 within the base 112 of the rotational support 116 canbe limited by the lip 113. The lip 113 can index or limit thedistal/proximal position of the ablation device 100 with respect to theendoscope distal end 128.

In general, in one aspect, the ablation device 100 includes a movementresistor 123 as shown in FIGS. 6, 7A-B, 8A-B, 9A-B, 10, 11A-C, and 12.In general, the movement resistor 123 is constructed and arranged topassively govern the rotational movement of the longitudinal support114. Advantages of the movement resistor 123 include reduction of theprofile of the ablation device 100. A reduced profile is useful whenaccessing and/or removing the ablation device 100 to and from a desiredtreatment area in a subject. For example, a reduced profile ablationdevice 100 can result in little or no lodging or catching of the device100 upon access or removal from an alimentary tract 1. Because thelongitudinal support 114 is generally free to move through one or moredegrees of freedom, the movement resistor 123 can advantageously serveto govern freedom of movement. In some embodiments the movement resistor123 includes an elastic or super elastic structure coupled with orattached to the longitudinal support 114. In other embodiments, themovement resistor 123 includes various other mechanical means to governrotational movement of the longitudinal support 114.

As illustrated in FIG. 6, in one embodiment the movement resistor 123includes a spring. It is envisioned that the spring can be a cantileverspring (as shown in FIG. 6), leaf spring, torsion spring or any of anumber of spring types, all of which are well known to those of skill inthe art. In one embodiment, as shown in FIG. 6, a cantilever springmovement resistor 123 can be constructed and arranged to restrictrotational movement of the longitudinal support 114 in relation to thedistal end 128 of an attached endoscope 127. As illustrated, thelongitudinal support 114 is generally maintained in a neutral positionby the spring of the movement resistor 123. As used herein, “neutralposition” means the longitudinal axis of the longitudinal support 114 issubstantially parallel to a longitudinal axis of an endoscope 127 orother elongate member connected to the ablation device 100. In oneembodiment, the movement resistor 123 is affixed to the rotationalsupport base or the strap or connecting element of the base, so that itapplies a pre-tension to the longitudinal support forcing the ablationdevice to be locked in its lowest profile position with respect to anattached endoscope 127 (not shown).

The movement resistor can be constructed and arranged to resistrotational movement of the longitudinal support and still permitforce-induced rotational deflection of the longitudinal support awayfrom the neutral position. In the absence of such force, someembodiments of the movement resistor tend to return to the longitudinalsupport to the neutral position. It is envisioned that the movementresistor can be constructed and arranged to affect rotational movementof the longitudinal support about one or more axes of movement.Furthermore, it is envisioned that different axes of movement (e.g., x,y and z axes; see FIG. 1) can be differentially affected by the movementresistor.

In another embodiment, as shown in FIGS. 7A-B, the movement resistor 123can include a sheath encapsulating electrical conductive wires 133. Thesheath can be made of an elastic or super elastic material, includingbut not limited to, for example, silicone. As shown in detail in FIG.7B, the sheath movement resistor 123 is connected at one end to thelongitudinal support 114. The opposite end of the sheath movementresistor 123 can be fixed in position relative to an endoscope 127 orother elongated structure by, for example, a sleeve 138 (see FIGS.7A-B). In the embodiment shown in FIGS. 7A-B, the electrical conductivewires 133 can include a zigzag pattern. The pattern can permitlengthening of the electrical conductive wires 133 when the movementresistor 123 is lengthened.

In yet another embodiment, as shown in FIGS. 8A-B, the movement resistor123 can include a band of elastic or super elastic material coupled withor attached to the longitudinal support 114. Suitable elastic or superelastic materials can include but are not limited to silicone. Asillustrated in FIG. 8A, in one embodiment the movement resistor is aband of elastic or super elastic material looped over and connecting aportion of the longitudinal support 114 with an endoscope 127. Asillustrated in FIG. 8B, in another embodiment, the movement resistor 123is a band of elastic or super elastic material connecting a portion ofthe longitudinal support 114 with an endoscope 127. In the example shownin FIG. 8B, the band is connected to the endoscope 127 by way of asleeve 138 attached to the endoscope 127.

In a further embodiment, as shown in FIGS. 9A-B, the movement resistor123 can include a stay or tether attached to a portion of thelongitudinal support 114. A portion of the stay or tether can beconnected to the endoscope 127 by way of a sleeve 138 attached to theendoscope 127. The movement resistor 123 of this embodiment cangenerally maintain the longitudinal support 114 in a neutral positionwhen the distal end 128 of an endoscope 127 attached to the ablationdevice 100 is arranged in a relatively straight configuration. When theendoscope distal end 128 is deflected as shown in FIG. 9B, the stay ortether of the movement resistor 123 can slacken or gather on itself. Inone embodiment the movement resistor 123 stay or tether is constructedand arranged such that upon slackening it collapse upon itself in anaccordion-like manner (see FIG. 9B).

In another embodiment, as shown in FIG. 10, the movement resistor 123can include a finger 121 component, and a recess 122 component. Thefinger 121 can be connected to an endoscope 127 by way of a sleeve 138or other attachment means, and the recess 122 can be included in thelongitudinal support 114. As shown in FIG. 10, the finger 121 can engagethe recess 122 thereby maintaining the longitudinal support 114 in aneutral position when the distal end 128 of an endoscope 127 attached tothe ablation device 100 is arranged in a relatively straightconfiguration. The finger 121 and recess 122 can be constructed andarranged such that deflection of the endoscope distal end 128 orapplication of force to portions of the longitudinal support 114 canreversibly release the finger 121 from the recess 122. Once the finger121 is released, the longitudinal support 114 is freed for rotationalmovement. Reconnection of the finger 121 and the recess 122 once againmaintains the longitudinal support 114 in a neutral position.

As shown in FIGS. 11A-C, in one embodiment the movement resistor 123 isa skirt or train connected to a portion of the longitudinal support 114and extending proximally down the length of a connected endoscope 127.In this embodiment the skirt or train of the movement resistor 123 fitsover a proximal end of the longitudinal support 114 or juxtaposition tothe proximal end of 114. This arrangement provides a smooth profile tothe proximal portion of the longitudinal support 144. Such a profile isuseful for easing removal of the ablation device 100 from a treatmentregion by reducing the risk of the support 114 lodging or catching on atissue surface. The movement resistor 123 can be attached to thelongitudinal support 114 as shown in FIG. 11A or 11B to longitudinalsupport 114 or alternatively not be attached.

It is envisioned that one or more of the above described movementresistors can be included in a single ablation device to governrotational movement of the longitudinal support. It is also envisionedthat attachment of a portion of movement resistor to an endoscope,catheter or other structure can include any of a number of attachmentmeans in addition to a sleeve attachment. For example, the movementresistor can be attached to an inside or outside surface of an endoscopeor catheter or a feature thereof (not shown).

In general, in one aspect, the ablation device 100 includes an actuatormechanism 134 for actively governing the rotation of the longitudinalsupport 114 (see e.g., FIG. 12). Generally the actuator mechanism 134permits interconversion between a rotationally constrained longitudinalsupport 114 and free rotation of the support 114. As shown in FIG. 12,in one embodiment the actuator mechanism 134 includes a switch 135 and astay 136 or tether. The switch 135 of the actuator mechanism 134 can becoupled to an endoscope 127 connected to the ablation device 100. Thestay 136 can be connected to a portion of the longitudinal support 114.In the embodiment shown in FIG. 12, the switch 135 of the actuatormechanism 134 is attached to an endoscope by a sleeve 138 and can bepositioned in one or more positions including the positions “A” and “B”as indicated. Switching the actuator mechanism 134 to position “A”causes the stay 136 to pull on and thereby immobilize the rotationalfreedom of the longitudinal support 114. Additionally, when in the “A”position, the support 114 is caused to be maintained in a neutralposition. Switching the actuator mechanism 134 to position “B” relaxesthe stay's 136 pull on the longitudinal support 114 thereby allowing forrotational movement of the support 114.

In another embodiment, the actuator mechanism includes a vacuum line(not shown). In this embodiment, rotational movement of the longitudinalsupport is governed by suction provided by a vacuum line constructed andarranged such that a proximal portion of the support can be immobilizedwhen vacuum is applied. In the absence of the vacuum the longitudinalsupport would be able to rotate freely.

In yet another embodiment, the actuator mechanism is constructed andarranged such that rotational movement of the longitudinal support isgoverned by an electromagnet (not shown). In this embodiment,application of electromagnetic force causes immobilization of thelongitudinal support in a neutral position. Accordingly, when theelectromagnetic force is no long applied the support is able to rotatefreely.

The ablation structure, in one embodiment is an electrode structureconstructed and arranged to deliver energy comprising radiofrequencyenergy to tissue of an alimentary tract. It is envisioned that such anablation structure can include a plurality of electrodes. For example,two or more electrodes can be part of an ablation structure. The energymay be delivered at appropriate levels to accomplish ablation of mucosalor submucosal level tissue, or alternatively to cause injury to thesetissues, while substantially preserving muscularis tissue. The term“ablation” as used herein means thermal damage to the tissue causingtissue or cell necrosis. Thermal damage can be achieved through heatingtissue or cooling tissue (i.e. freezing). Typically, ablation in thepresent embodiments is designed to remove the entire mucosal lining inthe treatment region, including abnormal mucosa, for example, abnormalcolumnar growths, from the portions of the esophagus so affected, andallow re-growth of a normal mucosal lining. Advantageously, healing ismore rapid and stricture formation in the tissues is minimized when suchan approach is used. Also, the electrode ablation element could allowfluids such as saline to permeate through the longitudinal supportand/or the electrode to prevent tissue sticking to the electrode duringan ablation.

Although radiofrequency energy is one advantageous form of energy forablation, it is recognized that other advantageous energy formsincluding, for example, microwave energy, or photonic or radiant sourcessuch as infrared or ultraviolet light, the latter possibly incombination with improved sensitizing agents. Photonic sources caninclude semiconductor emitters, lasers, and other such sources. It isalso recognized that another embodiment of this invention may utilizeheatable fluid or a cooling media such as liquid nitrogen, Freon®, nonCFC refrigerants or CO₂ as an ablation energy medium. For ablationsusing hot or cold fluids or gases, it is envisioned that the ablationsystem may require a means to circulate the heating/cool media fromoutside the patient to the heating/cooling balloon or other element andthen back outside the patient again. Means for circulating media incryosurgical probes are well known in the ablation arts. For example,and incorporated by reference herein, suitable circulating means aredisclosed in U.S. Pat. No. 6,182,666 to Dobak, III; U.S. Pat. No.6,237,355 to Li; and U.S. Pat. No. 6,572,610 to Kovalcheck et al.

The ablation structure can include a bipolar array of electrodespositioned on the structure capable of delivering radiofrequency energyin a bipolar fashion. Alternatively, the ablation structure may includea monopolar electrode structure can be energized by a radiofrequencypower supply in combination with a return electrode typically positionedon the subject's skin, for example, on the small of the back. In eithercase, the radiofrequency energy can be delivered at a high energy fluxover a very short period of time in order to injure or ablate only themucosal or submucosal levels of tissue without substantially heating orotherwise damaging the muscularis tissue. Wherein the ablation structureincludes a plurality of electrodes, one or more of the electrodes can bebipolar or monopolar. Combinations of bipolar and monopolar electrodesare envisioned.

As shown in FIGS. 1A, 3A, 4A, 5, 6, and 7A-B, the ablation structure 130can be constructed and arranged in any of a number ways with regard toshape and size. As shown in FIGS. 3A, 4A, 7A-B and 14A-C, the ablationstructure 130 can include an electrode array 132. Where the ablationstructure 130 includes an electrode array 132, the array typically hasan area in the range from substantially 0.5 cm² to 9.0 cm². Typicalarray shapes would include square, rectangular, circular or oval. In oneembodiment, the ablation structure 101 has an area of 2.5 cm². Inanother embodiment, the ablation structure 101 has an area of 4 cm² anddimensions of 2 cm×2 cm.

The longitudinal support is constructed and arranged to support theablation structure. The support 114 can be made of any suitable materialfor withstanding the high energy flux produced by the ablation structure130. The longitudinal support can be flexible, enabling rotation abouttwo axes, thereby further permitting rotation of the longitudinalsupport away from the longitudinal axis (not shown). In one embodimentthe longitudinal support is made of an elastic material, for example,silicone. Other suitable materials include, for example, urethanes orother polymers.

As shown in FIGS. 3A, 4A-B, 7A-B and 14A-C, the ablation device 100 canfurther include electrical connections including conductive wires 133 toconnect the ablation structure 130 to a power source. The conductivewires 133 can include a single wire or plurality of wires as needed toprovide controlled energy delivery through the ablation structure. Inone embodiment, the conductive wires 133 include low electrical losswires such as litz wire. As shown in FIGS. 4A-B, the conductive wires133 can be wrapped or drawn over a distal end of the longitudinalsupport 114 and pass beneath the support 114. Such an arrangementadvantageously facilitates rotational movement of the longitudinalsupport 114 by preventing binding or restriction of rotational movement.

As shown in FIGS. 4A-B and 14A-C, the ablation device 100 can furtherinclude one or more electrode trace 131. The one or more electrode trace131 can be constructed and arranged to conform to at least a portion ofthe longitudinal support 114. The one or more trace 131 can be inelectrical communication with an electrode 132 and conductive wire 133.It is envisioned that the trace 131 can be an extension of electrode 132or a separate element. As shown in FIGS. 14A-C, the one or more trace131 can be in electrical communication with conductive wire 133 througha junction 140 feature. As shown, the junction 140 can be attached tothe connecting element 120 of the base 112. It is envisioned that theconductive wires 133 can be removably connected to the ablation deviceby way of the junction 140 wherein the junction is constructed andarranged, for example, as an electrical connector.

It is also recognized that another embodiment of this invention mayutilize heatable fluid or a cooling media such as liquid nitrogen,Freon®, non CFC refrigerants or CO₂ as an ablation energy medium. Forablations using hot or cold fluids or gases, it is envisioned that theablation system may require a means to circulate the heating/cool mediafrom outside the patient to the heating/cooling balloon or other elementand then back outside the patient again. Means for circulating media incryosurgical probes are well known in the ablation arts. For example,and incorporated by reference herein, suitable circulating means aredisclosed in U.S. Pat. No. 6,182,666 to Dobak, III; U.S. Pat. No.6,193,644 to Dobak, III et al.; U.S. Pat. No. 6,237,355 to Li; and U.S.Pat. No. 6,572,610 to Kovalcheck et al.

Accordingly, in another embodiment, as shown in FIG. 4C, the ablationstructure 130 can be constructed and arranged for cryogenic ablation oftissue. In general, the longitudinal support 114 can support or serve asthe ablation structure 130 by providing a conduit or support for thedelivery of the cooling fluid to enable cryogenic ablation of tissue. Inone implementation the ablation structure can be a balloon orballoon-like structure capable of being filled with fluid or gas (notshown). In another implementation, the ablation structure includes acapsule or box-like element covering a portion or all the surface of thelongitudinal support, which can be filled with fluid or gas (not shown).In one implementation the longitudinal support is partially orcompletely hollow for receiving a fluid or gas. It is envisioned thatthe ablation structure or the longitudinal support can include athermally conductive material for facilitating thermal transfer toeffect cryogenic ablation of a tissue. It is also envisioned that theablation structure or longitudinal support can include a thermallyconductive feature covering all or a portion of its surface. Forexample, a suitable thermally conductive feature could be a thinmetallic surface including but not limited to stainless steel ortitanium.

It is envisioned that the ablation structure or longitudinal support canin some implementations are constructed and arranged to be permeable toheating or cooling agents (not shown). As such, it is further envisionedthat the agent(s) can leach through the ablation structure orlongitudinal support, thereby allowing for direct contact between theagent(s) and a tissue surface.

As shown in FIG. 4C, delivery of cooling fluid to the ablation structure130 can include one or more line 144 and optionally one or more port142. The line 144 can be constructed and arranged to transport fluidincluding super-cooled fluid. The port 142 can provide a connectionbetween a line 144 and the ablation structure 130. The port 142 can becoupled directly to the longitudinal support 142. In one embodiment, theport is coupled to the longitudinal support and provides a conduit to anablation structure associated with the support (not shown).Alternatively, the port 142 can be directly coupled to an ablationstructure (not shown). In some implementations, line 144 is connected tothe longitudinal support 114 by way of a port 142 (see FIG. 4C). Theports can include a nozzle or other features useful for producing aphase change in gas or liquid often accomplished through achievingpressure differential.

By way of example, as illustrated in FIG. 4C one implementation includestwo lines 144 coupled with ports 142. The lines 144 both extend down thelength of the attached endoscope 127 (only one line 144 visibly extendsdown the length of the endoscope 127 in the view shown in FIG. 4C). Theports 142 are directly connected to the underside of the longitudinalsupport 114 and the upper surface of the longitudinal support 114 servesas the ablation structure 130. The longitudinal support 114 can besubstantially hollow to permit entry of an agent such as a heated orcooling fluid.

Optionally, the lines of the device can provide a return circuit for theflow of fluid to and from the ablation structure. For example, as shownin FIG. 4C, in one implementation where two lines 144 and two ports 142are employed, one line 144 can serve as an input line while the othercan serve as an outflow line.

In use, heated or super-cooled fluid can be delivered through the inputline to the ablation structure, thereby activating the ablationstructure. Activating the ablation structure with super-cooled fluid caninclude the induction of a phase change from liquid to gas or throughgeneration of a pressure differential such as a pressure drop (given theIdeal Gas Law: PV=nRT). Cryogenic ablation of tissue can be achieved bycontacting tissue with the super-cooled ablation structure. Optionally,a continuous flow of a heated or super-cooled fluid agent can bemaintained in the ablation structure by continuous or discontinuous flowof the agent into the ablation structure and out through the outflowline. If desired, after ablation, the agent can be removed from theablation structure. Optionally, after removal of the super-agent,another fluid, gas or air, having a desired temperature, can beintroduced into the ablation structure.

In general, in another aspect a method of ablating tissue in analimentary tract 1 includes advancing an ablation device 100 includingan ablation structure 130 (here an electrode 132) into the alimentarytract 1 (see e.g., FIG. 4A). The ablation structure 130 is supportedwith a structural support 111 within the alimentary tract 1. At least apart of the ablation structure 130 can be rotated away from thestructural support 111 and directed toward a tissue surface 5. Theablation structure 130 can be activated as desired to ablate the tissuesurface 5.

As illustrated in FIG. 4A, in one embodiment, rotating at least part ofthe ablation structure 130 (shown here as an electrode 132) includes theapplication of force between the ablation structure 130, for example, anelectrode 132 and the tissue surface 5. In another embodiment whereinthe ablation device 100 includes multiple ablation structures 130 (seefor example, FIG. 5) the rotating step includes applying force betweenone or more ablation structures 130 and the tissue surface 5.

The method of ablating tissue in an alimentary tract can further includerotating at least part of the ablation structure about at least onerotation axis, and/or about at least two rotation axes, and/or about atleast three rotation axes. As discussed in detail above, the ablationdevice can be constructed and arranged to support such movement. Forexample, as shown in FIG. 1, the support structure 111 of the ablationapparatus 100 can include a longitudinal support 114 and a rotationalsupport 116. The ablation structure 130 is supported by the longitudinalsupport 114, while the rotational support 116 is adapted to permitrotation of at least part of the ablation structure 130. Variousstructural aspects relating to rotational movement of the ablationstructure 130 of the present method are discussed in detail above.

In another embodiment, the method of rotating at least part of theablation structure includes limiting the range of rotation of theablation structure. Various structural aspects of features relating tolimiting the range of rotation in x, y and z axes are discussed above.For example, various rotational supports are disclosed as providingdegrees of freedom of movement in relation to x, y and z axes.

In a further embodiment, the method includes resisting rotation of theablation structure while rotating the structure. As discussed above, theablation device can include various movement resistor structuralfeatures constructed and arranged to resist rotational movement of theablation structure. For example, movement resistors are disclosed thatgovern rotational movement of the longitudinal support and thereby theablation structure.

In one embodiment, as illustrated in FIG. 4A, the step of advancing theablation structure 130 comprises advancing an endoscope 127 into thealimentary tract 1. An example of one commercially availableconventional endoscope 127 is the Olympus “gastrovideoscope” modelnumber GIF-Q160. While the specific construction of particularcommercially available endoscopes may vary, as shown in FIG. 13, mostendoscopes include a shaft 164 having a steerable distal end 128 and ahub or handle 162 which includes a visual channel 161 for connecting toa video screen 160 and a port 166 providing access to an inner workingchannel within the shaft 164. A power supply 159 can provide power tothe endoscope 127 by way of a power cable 165. Dials, levers, or othermechanisms (not shown) will usually be provided on the handle 162 toallow an operator to selectively steer the distal end 128 of theendoscope 127 as is well known in the endoscopic arts. In use, whereinthe ablation device 100 is coupled or connected to the endoscope 127,the combination can be introduced into and advanced within an alimentarytract. In an alternative embodiment, the step of advancing the ablationstructure comprises advancing a catheter into the alimentary tract (notshown).

As shown in FIG. 4A, in one embodiment the method includes supportingthe ablation structure (shown as an electrode 132) with the endoscope127. In use, as illustrated in FIG. 4A, the ablation device 100,including the ablation structure (shown as an electrode 132), can beattached to the endoscope distal end 128 for support thereof. Asdiscussed above in detail, in some embodiments the rotational support116 further includes a base 112 constructed and arranged to connect theablation device 100 to the endoscope 127. As such, the base 112 canprovide an attachment point for support of the ablation device 100 bythe endoscope 127.

In another method, the step of advancing an ablation device including anablation structure into an alimentary tract includes advancing anendoscope into the alimentary tract and advancing the ablation deviceover the endoscope. For example, the endoscope can be positionedrelative to an ablation target tissue after which the ablation devicecan be advanced over the outside of the endoscope for ablating thetarget tissue.

In another method the step of supporting the ablation device can includeinserting an endoscope into the ablation device after the ablationdevice has been advanced into the alimentary tract. As disclosed indetail in co-pending U.S. patent application Ser. Nos. 11/286,257 and11/286,444, filed Nov. 23, 2005, the full disclosure of which are fullyincorporated herein by reference, variously adapted and configuredablation structures can fit within and be conveyed through an endoscopeinternal working channel. As such the ablation structure of the ablationdevice can alternatively be supported by an internal working channel ofan endoscope. It is envisioned that combinations of any of the methodsdescribed herein for supporting the ablation device are possible.

In another embodiment of the method, where the ablation structure is atleast one electrode, the step of activating the ablation structure caninclude supplying electrical energy to the electrode by way ofelectrical connections (see e.g., FIGS. 3A, 4A-B, 7A-B and 14A-C).

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

1. An ablation device comprising: an ablation element; and a supportstructure adapted to support the ablation element within an alimentarytract of a patient, the support structure comprising a longitudinalsupport with a longitudinal axis and a rotational support, therotational support comprising: a base with a connecting element toconnect the longitudinal support to an endoscope and a pin about whichthe longitudinal support is arranged such that it can rotate withrespect to the longitudinal support's longitudinal axis; and a movementresister configured to resist rotation of the longitudinal support. 2.The device of claim 1 wherein the movement resistor is coupled to therotational support.
 3. The device of claim 1 wherein the movementresistor is disposed between the longitudinal support and the base. 4.The device of claim 1 wherein the movement resister comprises acantilever connected at its proximal portion to the base.
 5. The deviceof claim 1 wherein the movement resistor comprises a spring.
 6. Thedevice of claim 1 wherein the movement resistor comprises a superelastic material.
 7. The device of claim 1 wherein the movement resistoris arranged to resist rotational movement of the ablation element withrespect to the longitudinal support's longitudinal axis.
 8. The deviceof claim 1 wherein the movement resistor is configured to still permitforce-induced rotation of the ablation element with respect to supportstructure's longitudinal axis.
 9. The device of claim 1 wherein themovement resistor is configured to apply a tension to the longitudinalsupport such that it is biased to a neutral position wherein thelongitudinal support is substantially parallel to a longitudinal axis ofan endoscope to which the longitudinal support is attached.
 10. Thedevice of claim 1 further comprising an endoscope to which theconnecting element of the base is connected.
 11. A method of ablatingtissue in an alimentary tract comprising: advancing an ablation elementinto the alimentary tract, supporting the ablation element with alongitudinal support having a longitudinal axis; rotatably supportingthe longitudinal support such that the longitudinal support can rotatewith respect to the longitudinal support's longitudinal axis; andresisting rotation of the longitudinal support away from a neutralposition wherein the longitudinal axis of the longitudinal support issubstantially parallel to a longitudinal axis of an endoscope to whichthe longitudinal support is connected.
 12. The method of claim 11wherein rotatably supporting the longitudinal support comprisessupporting the longitudinal support about a pin.
 13. The method of claim11 wherein the resisting rotation step comprises resisting rotation inresponse to a force deflecting the longitudinal support away from theneutral position.
 14. The method of claim 11, further comprising forcingthe rotation of the longitudinal support about its longitudinal axisaway from the neutral position during the resisting step.
 15. The methodof claim 14 further comprising returning the longitudinal axis of thelongitudinal support to the neutral position after the rotating step.16. The method of claim 11 wherein resisting rotation comprisespassively resisting rotation.
 17. The method of claim 11 whereinresisting rotation comprises resisting rotation with a spring.
 18. Themethod of claim 17 wherein resisting rotation with a spring comprisesresisting with a cantilever spring.
 19. The method of claim 11 whereinresisting rotation comprises reducing a profile of an ablation devicecomprising the ablation element during the advancing step.